In this work, nanocomposites of poly(hydroxybutyrate‐co‐hydroxyvalerate) PHBV and multiwalled carbon nanotubes (MWNT) were prepared by melt blending. Mechanical, thermal, morphological, and electrical properties of the prepared PHBV/MWNT nanocomposites were investigated. Differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) results showed MWNT effectively enhanced the crystallization and nucleation of PHBV. Dynamic thermo‐mechanical and static uniaxial mechanical tensile and compressive properties were increased by the addition of MWNT. MWNT observed in the nanocomposites using transmission electron microscopy (TEM) showed dimensions similar to separated nanotubes inferring a good dispersion. The presence of nanotubes in close vicinity with each other formed an interconnecting network that led to the formation of electrically conductive nanocomposites. The electrical resistance of the nanocomposites was reduced with the addition of MWNT. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Composites of polyvinylidene fluoride (PVDF)/carbon nanofibers (CNFs) with different nanofiber contents were prepared by melt-blending using a twinscrew extruder by directly mixing CNFs with PVDF in the molten state. Fibers were extruded from the blended pellets. CNFs improved the nucleation efficiency of PVDF but the percent crystallinity decreased with increasing CNF concentration. X-ray diffraction results showed a change in the a phase, but the transition to the b phase did not occur. Dynamic mechanical analysis (DMA) indicated an improvement in storage modulus and reduced damping factor with increasing CNF concentration. A complementary improvement in mechanical properties was determined from tensile test results. Rheological measurements indicated increased storage modulus, loss modulus, and viscosity values with an increased percentage of CNFs in the PVDF.

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Nanocomposites were prepared by melt blending of multiwalled carbon nanotubes (MWCNTs) filled with polyvinylidene fluoride. Time-dependent piezoresistance was investigated as a function of concentration. In the quasi-static case, a transition from negative pressure coefficient to positive pressure coefficient (PPC) behavior was observed. The PPC effect was negligible at high concentrations. At short times, the resistive response decreased for all nanocomposites, with the magnitude of the decrease proportionate to the MWCNT concentration. However, long-term creep response was resistive for low concentrations and conductive at high concentrations. A Burgers model based on Maxwell and Kelvin elements in series was used to describe the strain dependence. An equivalent model that uses resistances and capacitances was examined for the time dependence of fractional resisitivity. Results were correlated with Raman mapping-based dispersion analysis. An increased dispersion and an increase in MWCNT-MWCNT contact area resulted in a transition from a matrix-based resistive response to a filler-based conductive response.